Preliminary UXO survey - Phase 1

Unexploded Ordnance (UXO) from the Second World War is sometimes encountered during excavation and dredging work. This can lead to dangerous situations. With a preliminary UXO investigation, T&A can determine whether there is an increased risk  of explosives. Reasons for conducting a preliminary UXO investigation may be planned earth-moving activities in post-war undisturbed soil or indications of combat and bombing in or near the research area.

T&A has already carried out many preliminary UXO surveyss throughout the Netherlands. In addition, T&A has mapped out the entire Dutch railway, cable and gas pipeline routes, rivers and dikes over a tens to hundreds of kilometers. As a result, we have an extensive archive with historical data.

The preliminary UXO investigation consists of two phases, in which several activities are carried out:

I - Inventory of source material

  • Literature study
  • Archival research
  • Interviews with local inhabitants and eye witnesses
  • Aerial photography interpretation

II - Assessment of the source material
This phase will only be carried out if the problem inventory gives rise to it:

  • Assessment of the inventory
  • Horizontal and vertical delimitation of the suspect area
  • Determination of the explosives types

The end result of the research is a report and an inventory map in GIS. This indicates where and at what depth there may be explosives and of what type.

In a project specific risk analysis (PRA) the risk of UXO presence in the subsurface is mapped in order to deterimine how the planned activities can take place in a safe way.

The PRA is not a mandatory step between the historical preliminary research and te field research (detection and approach of UXO). In some cases however the PRA can be of added value to reduce time and costs:

  • During the historical preliminary research the suspect areas have not yet been been vertically defined and the post-war groundworks have not yet been mapped.
  • The planned activities are very diverse and extensive and the UXO research is likely to be expensive and has to take place in a restricted timespan.

T&A's archive contains historical data of almost every municipality in the country. We would like to use this information in your favour!

Experience tought us most municipalities have a seperate historical research perfomed for every single project involving earthworks. In growing communities the research costs can become very high over the years. A once-off investment in a community wide historical preliminary research generally costs five times as much as an individual one and will therefor pay off quickly. Municipalities T&A has already performed a historical research project for are Deventer, Haarlemmermeer, Tiel and Voorst.

Advantages of a community wide historical research project:

  • Great service from municipality to its citizens, project developers and city administration;
  • Information about UXO risk is always at hand;
  • Risk calculation of projects made easier;
  • Independence of interpretation of other parties;
  • No necessity for last-minute, emergency UXO surveys;
  • Valuable document for city development planning.

Many factors must be taken into account when carrying out earth-moving activities. The availability of information about the soil can reduce costs during implementation. With T&A's Omni soil scan, the risk of high additional costs can be considerably reduced at a limited, fixed rate.

What is the Omni soil scan?
The Omni soil scan is a desk study that provides insight into the possible risks in the field of archeology, geotechnical or hydrological soil composition, pollution, foundation remains, UXO, cables and pipes. Archive material and aerial photos from different periods are used for this.

Omni Soil scan plus
The Omni soil scan plus complements this desk survey with several drillings and probes and a geophysical field survey to immediately identify potential risks.

Benefits of the Omniscan   
T&A has specialists in several fields under one roof, which means the client receives a single report with the conclusions of several disciplines.

T&A Survey has performed Preliminary UXO resarch for (amongst others):



Gemeente Haarlemmermeer

Hoogheemraadschap van Schieland en Krimpenerwaard

Gemeente Voorst

Antea Group

Gemeente Tiel

Movares Nederland


Gemeente Deventer

Rijkswaterstaat Zee en Delta

Sweco Nederland

Gemeente Roerdalen

Witteveen + Bos

Waterschap Hollandse Delta